A low-temperature sintering bone china enamel formula containing rare earth and zirconium and a process thereof

Abstract

This invention discloses a low-temperature sintering bone china glaze formula and process containing rare earth synergistic zirconium, belonging to the field of bone china glaze technology. The process includes: S1, raw material pretreatment; S2, ingredient mixing; S3, high-temperature melting; and S4, ball milling to glaze slurry. This low-temperature sintering bone china glaze formula and process, through the rational combination of fluxes such as Li2O, Na2O+K2O, and B2O3, combined with the synergistic effect of rare earth oxides and ZrO2, lowers the glaze firing temperature to 1080℃-1120℃. Compared to traditional high-temperature glaze firing processes (above 1200℃), this significantly reduces energy consumption and production costs. Simultaneously, low-temperature sintering effectively avoids defects such as body deformation, glaze dripping, pinholes, and glaze chipping. Combined with optimization of the preparation and glazing firing processes, this significantly improves the yield of bone china products, solving the technical pain points of high energy consumption and low yield in traditional high-temperature sintering of bone china.

Description

Technical Field

[0001] This invention belongs to the field of bone china glaze technology, specifically relating to a low-temperature sintering bone china glaze formula and process containing rare earth synergistic zirconium. Background Technology

[0002] Bone china, as a high-end daily-use ceramic, is widely used in tableware, decorative utensils, and other fields due to its delicate texture, good translucency, warm luster, and excellent mechanical properties. The core characteristic of bone china is that the body contains a certain amount of bone ash (mainly tricalcium phosphate). The quality of its glaze directly determines the appearance, performance, and lifespan of the bone china. Currently, traditional bone china glazes mostly employ high-temperature sintering processes, with firing temperatures typically above 1200℃. High-temperature sintering not only consumes a large amount of energy and increases production costs but also easily leads to defects such as body deformation, glaze dripping, pinholes, and glaze chipping, reducing the product qualification rate.

[0003] Existing technologies often lower the melting point of glazes by adding large amounts of flux. However, excessive addition of flux can lead to decreased glaze hardness, reduced wear resistance, and decreased chemical stability, failing to meet the high-end application requirements of bone china. Furthermore, ZrO2, a commonly used glaze modifier, can improve glaze hardness and wear resistance, but adding ZrO2 alone can easily cause cracks in the glaze, affecting its integrity. Rare earth oxides in ceramic glazes can refine grains and improve glaze gloss, but existing technologies often use single rare earth oxides, resulting in limited modification effects and failing to achieve a synergistic effect with ZrO2, thus failing to fully leverage the modifying advantages of both. Summary of the Invention

[0004] The purpose of this invention is to provide a low-temperature sintering bone china glaze formulation and process containing rare earth synergistic zirconium to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a low-temperature sintered bone china glaze formula containing rare earth synergistic zirconium, wherein the oxide composition of the glaze, by mass percentage, includes: The composition of the rare earth oxides is as follows: SiO2 55%~62%, Al2O3 10%-14%, ZrO2 4%-8%, Li2O 0.8%-1.5%, SrO 2%-4%, ZnO 3%-5%, CaO 2%-3%, BaO 1%-2%, B2O3 5%-7%, P2O5 2%-3%, Na2O+K2O 3%-5%, rare earth oxides 1.0%-2.5%, MgO≤1%, Fe2O3+TiO2≤0.3%, PbO 0%, CdO 0%. The rare earth oxide is a compound of CeO2, Y2O3 and La2O3, wherein CeO2 is 0.5%-1.2%, Y2O3 is 0.3%-0.8% and La2O3 is 0.2%-0.5%.

[0006] In a preferred embodiment, the oxide composition of the glaze is preferably: 58% SiO2, 12% Al2O3, 6% ZrO2, 1.0%-1.2% Li2, 3% SrO, 4% ZnO, 2.5% CaO, 1.5% BaO, 6% B2O3, 2% P2O5, 4.3% Na2O+K2O, 0.8% CeO2, 0.5% Y2O3, 0.3% La2O3, ≤0.8% MgO, and ≤0.2% Fe2O3+TiO2.

[0007] 3. The low-temperature sintered bone china glaze formulation containing rare earth synergistic zircon as described in claim 2, characterized in that: the ZrO2 is introduced by zircon, and the amount of zircon added in the formulation can generate the t-ZrO2 phase in the glaze; the P2O5 is provided by bone powder in the bone china body, thereby achieving self-synergistic bonding between the glaze and the body.

[0008] This invention discloses a process for preparing a low-temperature glaze for bone china containing rare earth synergistic zirconium, comprising the following steps: S1. Raw material pretreatment: Quartz and zircon are crushed to below 200 mesh, kaolin is dried to a moisture content of <1%, rare earth oxides are made of nano-sized powder, and all raw materials are treated to remove impurities to ensure that the total content of Fe2O3+TiO2 is ≤0.3%; S2. Ingredient mixing: Weigh each raw material according to the proportion corresponding to the oxide composition, put them into a horizontal rotary mixer and dry mix for 20-30 minutes to obtain a uniform mixture. S3. High-temperature melting: The mixture is added to a natural gas melting furnace at 1500℃ for melting, and an open flame oxidizing atmosphere is maintained throughout the process, wherein O2 > 3%. The melting is divided into five stages. Dehydration and degassing stage: slow drying at 1000℃, then adding materials in small batches at 1000–1200℃ to complete the evaporation of free water and water of crystallization and the decomposition of carbonates; Solid-state reaction stage: The temperature is increased to 1200–1400℃ at a rate of 3–5℃ / min to complete the eutectic melting and solid-state reaction of feldspar, quartz, etc., and form a low eutectic material; Melting and liquefaction stage: The temperature is raised to 1400–1500℃ to completely melt the material into a homogeneous glass liquid; Homogenization and clarification stage: Hold at 1500℃ for 1–3 hours to achieve homogenization of melt composition and clarification and removal of bubbles; Water quenching and granulation stage: The clarified high-temperature melt is discharged from the furnace body outlet and flows into the cold water pool for rapid cooling and cracking into granules. After being scooped out and dehydrated, qualified frit is obtained. The entire process from feeding to discharging takes 4–8 hours. S4. Ball milling to glaze slurry: By weight, take 100% frit, 3-5% kaolin, 45% water and an appropriate amount of CMC thickener, put the above materials into a ball mill, and add 200-220 parts of alumina ball milling media.

[0009] In a preferred embodiment, the stirring speed of the horizontal rotary mixer in step S2 is 150-200 r / min, and the machine is stopped and the material is turned over every 10 minutes during the mixing process to ensure that the raw materials are free of clumping and the components are evenly distributed.

[0010] In a preferred embodiment, after the glaze slurry is ball-milled in step S4, it is sieved through a 200-mesh sieve, and the viscosity of the glaze slurry after sieving is controlled at 300-500 mPa·s.

[0011] This invention also discloses a glazing and firing process for low-temperature sintered bone china containing rare earth synergistic zirconium, comprising the following steps: S1. Pre-treatment of the body: The bisque-fired bone china body is polished until the surface is smooth, free of burrs and chips. Surface dust is removed by blowing with compressed air. The bisque firing temperature is 1200℃-1250℃. The linear expansion coefficient of the bisque-fired body is 7.6-8.0×10⁻⁶. -6 / ℃; S2. Glazing: Apply glaze to the pretreated body using either a glazing pouring or spraying method. The glaze thickness should be controlled between 0.15mm and 0.25mm to ensure a uniform glaze layer without drips or pinholes. S3. Drying: Place the glazed body in a drying oven at 60℃-80℃ for 2-3 hours until the moisture content of the glaze layer is <0.5%; S4. Low-temperature glaze firing: The dried body is placed in a kiln and glazed at a low temperature in an oxidizing atmosphere. The glaze firing temperature is 1080℃-1150℃, and the holding time is 1.5h-2h. After firing, the body is cooled to room temperature in the kiln to obtain the finished bone china.

[0012] In a preferred embodiment, the heating rate of the glaze firing in step S4 is 3-5℃ / min. When the temperature reaches 500℃, it is kept at a constant temperature for 20 minutes. When the temperature reaches 800℃, it is kept at a constant temperature for 30 minutes. Then, the temperature is continued to rise to the glaze firing temperature to prevent the glaze layer from cracking or chipping.

[0013] In a preferred embodiment, the coefficient of thermal expansion of the bone china glaze layer after glazing and firing is 6.6-7.2 × 10⁻⁶. -6 / ℃, the difference in the coefficient of thermal expansion between the bone china and the body is controlled within 0.6-1.0×10. -6The temperature is within / ℃, and the microhardness of the glaze reaches 800-900HV, and the Mohs hardness is ≥7H.

[0014] In a preferred embodiment, the glaze of the finished bone china product showed no corrosion, loss of gloss, or glaze peeling after being soaked in 4% HCl at room temperature for 24 hours and 5% NaOH at room temperature for 24 hours.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention, through the rational combination of fluxes such as Li2O, Na2O+K2O, and B2O3, and the synergistic effect of rare earth oxides and ZrO2, lowers the glaze firing temperature to 1080℃-1150℃. Compared to traditional high-temperature glaze firing processes (above 1200℃), this significantly reduces energy consumption and production costs. Simultaneously, low-temperature sintering effectively avoids defects such as body deformation, glaze dripping, pinholes, and glaze chipping. Combined with optimizations in the preparation and glazing firing processes, this significantly improves the yield of bone china products, solving the technical pain points of high energy consumption and low yield associated with traditional high-temperature sintering of bone china. Furthermore, the gradient heating and heat preservation processes during frit melting and glaze firing further prevent raw material agglomeration and glaze cracking, enhancing product quality stability.

[0016] This invention utilizes a synergistic effect of CeO2, Y2O3, and La2O3 compound rare earth oxides with ZrO2, wherein ZrO2 exists in the t-ZrO2 phase. This synergistic effect with the compound rare earth oxides achieves comprehensive optimization of the glaze's performance: on the one hand, it significantly improves the microhardness (800-900 HV) and Mohs hardness (≥7H) of the glaze layer, enhancing its wear resistance and scratch resistance, and extending product lifespan; on the other hand, it refines the glaze grains, improving surface smoothness and gloss, thus enhancing the product's appearance quality; simultaneously, it enhances the glaze's toughness and crack resistance, preventing defects such as cracks and peeling. Compared to modification with single ZrO2 or single rare earth oxides, the synergistic modification effect of this invention is more significant, resulting in superior overall glaze performance.

[0017] The glaze preparation and glazing firing processes of this invention have clear steps and well-defined parameters, requiring no complex equipment or special operating conditions. Steps such as raw material pretreatment, batching and mixing, frit melting, ball milling and slurry preparation, as well as glazing, drying, and firing are all easily controlled, enabling large-scale, industrialized production. Furthermore, the raw materials used in the process are all conventional ceramic materials, widely available and inexpensive, further reducing production costs and enhancing the product's market competitiveness. In addition, the optimization of parameters such as ball milling media, heating rate, and holding time ensures product quality stability and facilitates quality control in industrial mass production. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the preparation process of the low-temperature sintering bone china glaze containing rare earth synergistic zirconium according to the present invention. Figure 2 This is a schematic diagram of the glazing and firing process of the low-temperature sintered bone china containing rare earth synergistic zirconium according to the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments.

[0020] The following embodiments are used to illustrate the present invention, but should not be used to limit the scope of protection of the present invention. The conditions in the embodiments can be further adjusted according to specific conditions, and simple improvements to the method of the present invention under the premise of the concept of the present invention are all within the scope of protection claimed by the present invention.

[0021] Please see Figures 1-2 This invention provides a low-temperature sintered bone china glaze formula containing rare earth synergistic zirconium. The oxide composition of this glaze, by mass percentage, includes: The composition of the rare earth oxides is as follows: SiO2 55%~62%, Al2O3 10%-14%, ZrO2 4%-8%, Li2O 0.8%-1.5%, SrO 2%-4%, ZnO 3%-5%, CaO 2%-3%, BaO 1%-2%, B2O3 5%-7%, P2O5 2%-3%, Na2O+K2O 3%-5%, rare earth oxides 1.0%-2.5%, MgO≤1%, Fe2O3+TiO2≤0.3%, PbO 0%, CdO 0%. The rare earth oxides are complexes of CeO2, Y2O3, and La2O3, with CeO2 accounting for 0.5%-1.2%, Y2O3 for 0.3%-0.8%, and La2O3 for 0.2%-0.5%.

[0022] SiO2, as the main skeleton component of the glaze, accounts for the highest proportion and determines the hardness and wear resistance of the glaze layer. At the same time, it participates in the formation of the glass phase, ensuring the transparency and gloss of the glaze layer. Al2O3 enhances the mechanical strength and chemical stability of the glaze, prevents the glaze from sagging at high temperatures, and can work synergistically with SiO2 to improve the toughness of the glaze and reduce glaze cracks. ZrO2 exists as the t-ZrO2 phase, which significantly improves the microhardness, wear resistance and impact resistance of the glaze layer, while refining the glaze grains and improving the smoothness of the glaze surface. It also works synergistically with rare earth oxides to further optimize the performance of the glaze layer. Li2O, Na2O+K2O are used as fluxes to lower the melting temperature of the glaze, enabling low-temperature sintering, while also improving the fluidity of the glaze and ensuring the uniformity of the glaze layer. The amount of Li2O added is controlled at 0.8%-1.5%, which can play a fluxing role without causing a decrease in the hardness of the glaze layer. SrO, ZnO, CaO, and BaO work synergistically as fluxing agents and modifiers. SrO can improve the gloss and transparency of the glaze, ZnO can enhance the toughness and crack resistance of the glaze, CaO can improve the chemical stability of the glaze, and BaO can refine the glaze grains and reduce glaze surface defects. B2O3 acts as a flux to further reduce the melting temperature of the glaze. At the same time, it can form a stable glass phase with SiO2 and Al2O3, which improves the transparency and gloss of the glaze and enhances the adhesion between the glaze and the body. Provided by the body bone powder, it can form complexes with other oxides in the glaze, achieving self-synergistic bonding between the glaze and the body, enhancing the bonding strength between the glaze layer and the body, and improving the light transmittance of the glaze layer; Rare earth oxides (CeO2, Y2O3, La2O3 compound): CeO2 can refine the glaze grains and improve the gloss and wear resistance of the glaze surface; Y2O3 can strengthen the glaze layer. The toughness and crack resistance of the glaze are improved, and the bonding performance between the glaze and the body is enhanced. La2O3 can improve the chemical stability and high temperature resistance of the glaze layer. The three work together to achieve comprehensive optimization of the glaze performance. MgO: As an auxiliary modifier, adding a small amount can improve the fluidity and smoothness of the glaze, but adding too much will cause pinholes in the glaze layer, so it should be controlled at ≤1%; PbO and CdO are strictly controlled to 0% to ensure the glaze is environmentally friendly and safe, meeting the environmental standards of modern daily-use ceramics and preventing the leaching of heavy metals from harming human health.

[0023] The preferred oxide composition of the glaze is: 58% SiO2, 12% Al2O3, 6% ZrO2, 1.0%-1.2% Li2, 3% SrO, 4% ZnO, 2.5% CaO, 1.5% BaO, 6% B2O3, 2% P2O5, 4.3% Na2O+K2O, 0.8% CeO2, 0.5% Y2O3, 0.3% La2O3, ≤0.8% MgO, and ≤0.2% Fe2O3+TiO2. This preferred formula can maximize the synergistic effect of each component and achieve optimal glaze performance.

[0024] ZrO2 is introduced from zircon, and the amount of zircon added to the ingredients can generate the t-ZrO2 phase in the glaze. P2O5 is provided by bone powder in the bone china body, achieving self-synergistic bonding between the glaze and the body. The t-ZrO2 phase has excellent toughness and hardness, which can significantly improve the wear resistance and crack resistance of the glaze layer. P2O5 is provided by bone powder in the bone china body, without the need for additional addition, achieving self-synergistic bonding between the glaze and the body, enhancing the bonding strength between the glaze layer and the body, and preventing the glaze layer from falling off.

[0025] This invention discloses a process for preparing low-temperature sintered bone china glaze containing rare earth synergistic zirconium, comprising the following steps: S1. Raw material pretreatment: Quartz and zircon are crushed to below 200 mesh, kaolin is dried to a moisture content of <1%, rare earth oxides are made of nano-sized powder, and all raw materials are treated to remove impurities to ensure that the total content of Fe2O3+TiO2 is ≤0.3%; S2. Ingredient mixing: Weigh each raw material according to the proportion corresponding to the oxide composition, put them into a horizontal rotary mixer and dry mix for 20-30 minutes to obtain a uniform mixture. S3. High-temperature melting: The mixture is added to a natural gas melting furnace at 1500℃ for melting, and an open flame oxidizing atmosphere is maintained throughout the process, wherein O2 > 3%. The melting is divided into five stages. Dehydration and degassing stage: slow drying at 1000℃, then adding materials in small batches at 1000–1200℃ to complete the evaporation of free water and water of crystallization and the decomposition of carbonates; Solid-state reaction stage: The temperature is increased to 1200–1400℃ at a rate of 3–5℃ / min to complete the eutectic melting and solid-state reaction of feldspar, quartz, etc., and form a low eutectic material; Melting and liquefaction stage: The temperature is raised to 1400–1500℃ to completely melt the material into a homogeneous glass liquid; Homogenization and clarification stage: Hold at 1500℃ for 1–3 hours to achieve homogenization of melt composition and clarification and removal of bubbles; Water quenching and granulation stage: The clarified high-temperature melt is discharged from the furnace body outlet and flows into the cold water pool for rapid cooling and cracking into granules. After being scooped out and dehydrated, qualified frit is obtained. The entire process from feeding to discharging takes 4–8 hours. S4. Ball milling to glaze slurry: By weight, take 100% frit, 3-5% kaolin, 45% water and an appropriate amount of CMC thickener, put the above materials into a ball mill, and add 200-220 parts of alumina ball milling media.

[0026] This invention also discloses a glazing and firing process for low-temperature sintered bone china containing rare earth synergistic zirconium, comprising the following steps: S1. Body Pretreatment: The bisque-fired bone china body is polished until smooth, free of burrs and chips, removing any unevenness to ensure a uniform glaze layer after glazing. Surface dust is removed by compressed air blowing to prevent it from affecting the bonding strength between the glaze and the body. The bisque-firing temperature is controlled at 1200℃-1250℃, and the coefficient of thermal expansion of the bisque-fired body is 7.6-8.0×10⁻⁶. -6 / ℃, this bisque firing parameter can give the body a certain strength, while controlling the coefficient of expansion of the body, laying the foundation for matching the coefficient of expansion of the glaze layer, and avoiding cracking of the glaze layer due to mismatch of expansion coefficients during the glaze firing process. S2. Glazing: Glaze the pretreated body using either a dipping or spraying method, with the glaze thickness controlled between 0.15mm and 0.25mm. Dipping and spraying methods ensure a uniform glaze coverage of the body surface. Controlling the glaze thickness guarantees both the decorative and protective effects of the glaze, while avoiding excessive thickness leading to drips and cracks, or insufficient thickness resulting in pinholes and exposed body defects. Ultimately, this ensures a uniform glaze layer free of drips and pinholes. S3. Drying: Place the glazed body in a drying oven at 60℃-80℃ for 2-3 hours until the moisture content of the glaze layer is <0.5%. Controlling the drying temperature and time can slowly remove moisture from the glaze layer, avoiding rapid evaporation that could cause cracking, while also ensuring that the dried glaze layer has a certain strength to facilitate subsequent glaze firing. S4. Low-temperature glaze firing: The dried body is placed in a kiln and glazed at a low temperature under an oxidizing atmosphere. The glaze firing temperature is controlled at 1080℃-1150℃, and the holding time is 1.5h-2h. After firing, the body is cooled to room temperature in the kiln to obtain the finished bone china.

[0027] The glaze firing process involves controlling the heating rate at 3-5℃ / min, holding the temperature at 500℃ for 20 minutes, holding it at 800℃ for 30 minutes, and then continuing to heat up to the firing temperature. This gradient heating and holding process avoids thermal stress in the glaze layer due to excessively rapid heating, preventing cracking and glaze chipping. The oxidizing atmosphere ensures the stability of the glaze components, preventing reduction reactions from affecting the glaze surface quality. The firing temperature is controlled at 1060℃-1120℃ to achieve low-temperature sintering, reducing energy consumption while ensuring the glaze layer is fully melted and tightly bonded to the body.

[0028] After glazing and firing, the coefficient of thermal expansion of the bone china glaze is 6.6-7.2 × 10⁻⁶. -6 / ℃, the difference in the coefficient of thermal expansion between the bone china and the body is controlled within 0.6-1.0×10. -6 Within a temperature range of / ℃, stress caused by thermal expansion differences in the glaze layer is effectively avoided, preventing cracking and peeling. The microhardness of the glaze layer reaches 800-900HV, and the Mohs hardness is ≥7H, exhibiting excellent wear resistance and scratch resistance. After soaking the glaze surface of the finished bone china product in 4% HCl at room temperature for 24 hours and 5% NaOH at room temperature for 24 hours, there is no corrosion, loss of gloss, or glaze peeling, indicating that the glaze layer has excellent chemical stability and can adapt to acidic and alkaline environments in daily use, extending the product's service life.

[0029] This invention reduces the glazing temperature to 1080℃-1150℃ by rationally combining fluxes such as Li2O, Na2O+K2O, and B2O3, and combining the synergistic effect of rare earth oxides and ZrO2. Compared with the traditional high-temperature glazing process (above 1200℃), this significantly reduces energy consumption and production costs.

[0030] Meanwhile, low-temperature sintering effectively avoids defects such as body deformation, glaze dripping, pinholes, and glaze chipping. Combined with optimization of the preparation and glazing firing processes, it significantly improves the yield of bone china products and solves the technical pain points of high energy consumption and low yield in traditional high-temperature sintering of bone china. In addition, the gradient heating and heat preservation processes during frit melting and glaze firing further prevent raw material agglomeration and glaze cracking, improving product quality stability.

[0031] This invention strictly controls the PbO and CdO content in the glaze to 0%, and simultaneously, through raw material impurity removal treatment, strictly controls the total Fe2O3+TiO2 content to ≤0.3% (preferably ≤0.2%), avoiding the leaching of heavy metals and the influence of impurities, ensuring the glaze is environmentally friendly and safe, and conforming to national standards such as GB / T 5003-2018 "Determination of Chemical Corrosion Resistance of Glaze Surfaces for Daily Use Ceramic Ware". It can be safely used in daily tableware and other fields, protecting human health, and solving the problems of traditional glazes containing heavy metals and having poor environmental performance.

[0032] This invention utilizes a synergistic effect of CeO2, Y2O3, and La2O3 compound rare earth oxides with ZrO2, wherein ZrO2 exists in the t-ZrO2 phase. This synergistic effect with the compound rare earth oxides achieves comprehensive optimization of the glaze's performance: on the one hand, it significantly improves the microhardness (800-900 HV) and Mohs hardness (≥7H) of the glaze layer, enhancing its wear resistance and scratch resistance, and extending product lifespan; on the other hand, it refines the glaze grains, improving surface smoothness and gloss, thus enhancing the product's appearance quality; simultaneously, it enhances the glaze's toughness and crack resistance, preventing defects such as cracks and peeling. Compared to modification with single ZrO2 or single rare earth oxides, the synergistic modification effect of this invention is more significant, resulting in superior overall glaze performance.

[0033] In this invention, P2O5 is provided by bone powder in the bone china body, requiring no additional addition. P2O5 can form complexes with other oxides in the glaze, achieving self-synergistic bonding between the glaze and the body. Simultaneously, the difference in the coefficient of thermal expansion between the glaze layer and the body is strictly controlled within 0.5 × 10⁻⁶. -6 Within a temperature range of / ℃, the bonding strength between the glaze and the body is significantly enhanced, effectively preventing glaze cracking and peeling. This solves the technical problem of poor glaze-body bonding in traditional bone china, improving the structural stability and service life of the product. This self-cooperative bonding method of glaze and body eliminates the need for additional binders, simplifying the process, reducing costs, and simultaneously improving the stability of the glaze-body bond.

[0034] The glaze preparation and glazing firing processes of this invention have clear steps and well-defined parameters, requiring no complex equipment or special operating conditions. Steps such as raw material pretreatment, batching and mixing, frit melting, ball milling and slurry preparation, as well as glazing, drying, and firing are all easily controlled, enabling large-scale, industrialized production. Furthermore, the raw materials used in the process are all conventional ceramic materials, widely available and inexpensive, further reducing production costs and enhancing the product's market competitiveness. In addition, the optimization of parameters such as ball milling media, heating rate, and holding time ensures product quality stability and facilitates quality control in industrial mass production.

[0035] The bone china products prepared by this invention not only have a smooth, high-gloss, and defect-free glaze, but also possess excellent mechanical properties and chemical stability. Compared to traditional bone china, the product quality is significantly improved, meeting the demands of the high-end market, increasing the added value of the products, and promoting the upgrading and development of the bone china industry. At the same time, the low-temperature sintering process reduces energy consumption and pollutant emissions, aligning with the development trend of green manufacturing, and yielding good economic and social benefits.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-temperature sintered bone china glaze formula containing rare earth synergistic zirconium, characterized in that, The oxide composition of this glaze, by weight percentage, includes: The composition of the rare earth oxides is as follows: SiO2 55%-62%, Al2O3 10%-14%, ZrO2 4%-8%, Li2O 0.8%-1.5%, SrO 2%-4%, ZnO 3%-5%, CaO 2%-3%, BaO 1%-2%, B2O3 5%-7%, P2O5 2%-3%, Na2O+K2O 3%-5%, rare earth oxides 1.0%-2.5%, MgO≤1%, Fe2O3+TiO2≤0.3%, PbO 0%, CdO 0%. The rare earth oxide is a compound of CeO2, Y2O3 and La2O3, wherein CeO2 is 0.5%-1.2%, Y2O3 is 0.3%-0.8% and La2O3 is 0.2%-0.5%.

2. The low-temperature sintering bone china glaze formulation containing rare earth synergistic zirconium according to claim 1, characterized in that: The preferred oxide composition of the glaze is: 58% SiO2, 12% Al2O3, 6% ZrO2, 1.0%-1.2% Li2, 3% SrO, 4% ZnO, 2.5% CaO, 1.5% BaO, 6% B2O3, 2% P2O5, 4.3% Na2O+K2O, 0.8% CeO2, 0.5% Y2O3, 0.3% La2O3, ≤0.8% MgO, and ≤0.2% Fe2O3+TiO2.

3. The low-temperature sintering bone china glaze formulation containing rare earth synergistic zirconium according to claim 2, characterized in that: The ZrO2 is introduced by zircon, and the amount of zircon added in the ingredients can generate the t-ZrO2 phase in the glaze. The P2O5 is provided by bone powder in the bone china body, realizing the self-synergistic bonding of glaze and body.

4. A process for preparing a low-temperature sintered bone china glaze containing rare earth synergistic zirconium, used to prepare the low-temperature sintered bone china glaze containing rare earth synergistic zirconium as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Raw material pretreatment: Quartz and zircon are crushed to below 200 mesh, kaolin is dried to a moisture content of <1%, rare earth oxides are made of nano-sized powder, and all raw materials are treated to remove impurities to ensure that the total content of Fe2O3+TiO2 is ≤0.3%; S2. Ingredient mixing: Weigh each raw material according to the proportion corresponding to the oxide composition, put them into a horizontal rotary mixer and dry mix for 20-30 minutes to obtain a uniform mixture. S3. High-temperature melting: The mixture is added to a natural gas melting furnace at 1500℃ for melting, and an open flame oxidizing atmosphere is maintained throughout the process, wherein O2 > 3%. The melting is divided into five stages. Dehydration and degassing stage: slow drying at 1000℃, then adding materials in small batches at 1000–1200℃ to complete the evaporation of free water and water of crystallization and the decomposition of carbonates; Solid-state reaction stage: The temperature is increased to 1200–1400℃ at a rate of 3–5℃ / min to complete the eutectic melting and solid-state reaction of feldspar, quartz, etc., and form a low eutectic material; Melting and liquefaction stage: The temperature is raised to 1400–1500℃ to completely melt the material into a homogeneous glass liquid; Homogenization and clarification stage: Hold at 1500℃ for 1–3 hours to achieve homogenization of melt composition and clarification and removal of bubbles; Water quenching and granulation stage: The clarified high-temperature melt is discharged from the furnace body outlet and flows into the cold water pool for rapid cooling and cracking into granules. After being scooped out and dehydrated, qualified frit is obtained. The entire process from feeding to discharging takes 4–8 hours. S4. Ball milling to glaze slurry: By weight, take 100% frit, 3-5% kaolin, 45% water and an appropriate amount of CMC thickener, put the above materials into a ball mill, and add 200-220 parts of alumina ball milling media.

5. The preparation process of a low-temperature sintering bone china glaze containing rare earth synergistic zirconium according to claim 1, characterized in that: In step S2, the horizontal rotary mixer operates at a speed of 150-200 r / min. During the mixing process, the mixer is stopped and the material is turned over every 10 minutes to ensure that the raw materials are free of clumping and that the components are evenly distributed.

6. The preparation process of a low-temperature sintered bone china glaze containing rare earth synergistic zirconium according to claim 1, characterized in that: After the glaze slurry is ball-milled in step S4, it is sieved through a 200-mesh sieve. The viscosity of the glaze slurry after sieving is controlled at 300-500 mPa·s.

7. A glazing and firing process for low-temperature sintered bone china containing rare earth synergistic zirconium, characterized in that, The glaze slurry prepared using the process described in any one of claims 4-6 is characterized by comprising the following steps: S1. Pre-treatment of the body: The bisque-fired bone china body is polished until the surface is smooth, free of burrs and chips. Surface dust is removed by blowing with compressed air. The bisque firing temperature is 1200℃-1250℃. The linear expansion coefficient of the bisque-fired body is 7.6-8.0×10⁻⁶. -6 / ℃; S2. Glazing: Apply glaze to the pretreated body using either a glazing pouring or spraying method. The glaze thickness should be controlled between 0.15mm and 0.25mm to ensure a uniform glaze layer without drips or pinholes. S3. Drying: Place the glazed body in a drying oven at 60℃-80℃ for 2-3 hours until the moisture content of the glaze layer is <0.5%; S4. Low-temperature glaze firing: The dried body is placed in a kiln and glazed at a low temperature in an oxidizing atmosphere. The glaze firing temperature is 1080℃-1150℃, and the holding time is 1.5h-2h. After firing, the body is cooled to room temperature in the kiln to obtain the finished bone china.

8. The glazing and firing process for low-temperature glazed bone china containing rare earth synergistic zirconium according to claim 7, characterized in that: In step S4, the heating rate for glaze firing is 3-5℃ / min. When the temperature reaches 500℃, it is kept at a constant temperature for 20 minutes. When the temperature reaches 800℃, it is kept at a constant temperature for 30 minutes. Then, the temperature is raised to the glaze firing temperature to prevent the glaze layer from cracking or chipping.

9. The glazing and firing process for low-temperature sintered bone china containing rare earth synergistic zirconium according to claim 7, characterized in that: The coefficient of thermal expansion of the bone china glaze layer after firing is 6.6-7.2×10⁻⁶. -6 / ℃, the difference in the coefficient of thermal expansion between the bone china and the body is controlled within 0.6-1.0×10. -6 The temperature is within / ℃, and the microhardness of the glaze reaches 800-900HV, and the Mohs hardness is ≥7H.

10. The glazing and firing process for low-temperature sintered bone china containing rare earth synergistic zirconium according to claim 7, characterized in that: The glaze of the bone china finished product showed no corrosion, loss of gloss, or glaze peeling after being soaked in 4% HCl at room temperature for 24 hours and 5% NaOH at room temperature for 24 hours.

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